Vitamin B12 or folate deficiency anaemia Diagnosis NHS
You should contact your GP if: You have been found to have elevated B12 levels on blood tests, particularly if levels exceed 1000 ng/L (approximately 740 pmol/L, though laboratory reference ranges vary) and you are not taking high-dose supplements You develop new symptoms after starting B12 supplementation, including persistent skin rashes, significant gastrointestinal disturbance, or unexplained symptoms You have underlying liver disease, kidney problems, or blood disorders and are considering B12 supplementation You are taking B12 supplements without medical supervision and have not had your levels checked, particularly if taking doses exceeding 2000 micrograms daily You experience symptoms that might indicate underlying disease, such as unexplained weight loss, persistent fatigue, jaundice, or abdominal swelling Call 999 or go to A&E if you develop severe allergic reactions following B12 injections, including difficulty breathing, facial swelling, or widespread rash, as these may indicate anaphylaxis, though this is extremely rare
The treatment starts with a big dose, then smaller doses are given regularly
The recommended vitamin B12 intake (in micrograms, or mcg) is as follows: *Adequate Intake S ource: National Institutes of Health Office of Dietary Supplements Unless you have a B12 deficiency or have identified a risk factor for deficiency (like following a vegan diet or having a malabsorption issue), theres no need to take a vitamin B12 supplement
